1. Field of Invention
The present invention relates to a digital filtering system and a method thereof, and more particularly to a digital filtering system and a method thereof, capable of analyzing physiological signal features, starting the most appropriate filter module, and continuously updating filter module coefficients and decision parameters on real time.
2. Related Art
In the prior art, no manner for which kind of physiological signal inspection operation, the noise filtering is the primarily processed operation.
However, on the market, filters include finite impulse response digital filters, infinite impulse response digital filters, high-pass digital filters, low-pass digital filters, medium frequency digital filters, band pass digital filters, and band rejection digital filters. However, digital filter types, retrieving frequencies, clocks, signal intensities, waveform heights of different physiological signals are different, for example, the physiological signals generated by blood pressure and blood oxygen are different.
Care device manufacturers need to preset care devices or physiological signal measuring devices to the most desired set value before sale. Alternatively, the care personnel continuously adjust the care devices or measuring devices to the set values which are most appropriate for users in a try error manner when using the care devices or measuring devices.
However, the prior art has inevitable disadvantages as follows.
Firstly, the change of the real-time signal cannot be anticipated, no matter how the care devices, the systems, or the measuring devices are optimally set by the people in the industry or the care personnel, as long as the user environment is changed, such as the change of seasons, the placement of appliance devices, or the carrying of portable electronic devices, and the change in the power supply of the electronic device provided with the disposed digital filter, the noise may be generated, such that the accuracy of the measured physiological signal is greatly lowered.
Secondly, the physiological signal is a real-time signal, but the coefficients of most of the digital filters are set to the initially designed ideal value. However, before the digital filter is practically applied to measure the physiological signal, as described above, it is continuously corrected to the most appropriate set value in the manual try error manner, thereby costing a great amount of time and manpower cost. Further, the filters finishing the setting are mostly only applicable to a single user instead of other users, thereby greatly lowering the adaptability of the filter.
Thirdly, electromechanical characteristics (for example, heat noise and circuit magnetic field) generated by an operating circuit of the digital filter may be received by the measuring device due to feedback, such that the noises are mixed in the physiological signal. However, the filter cannot determine whether the electromechanical characteristics are generated by the circuit thereof or not, so the noises generated by the electromechanical characteristics may not be prevented.